1. Field of the Invention
The field of the invention relates to electro-optical readers or scanning systems, such as bar code symbol readers, and more particularly to a scanning module for use in applications requiring particularly compact scanners.
2. Description of the Related Art
Electro-optical readers, such as bar code symbol readers, are now very common. Typically, a bar code symbol comprises one or more rows of light and dark regions, typically in the form of rectangles. The widths of the dark regions, i.e., the bars, and/or the widths of the light regions, i.e., the spaces, between the bars indicate encoded information to be read.
A bar code symbol reader illuminates the symbol and senses light reflected from the coded regions to detect the widths and spacings of the coded regions and derive the encoded information. Bar code reading type data input systems improve the efficiency and accuracy of data input for a wide variety of applications. The ease of data input in such systems facilitates more frequent and detailed data input, for example to provide efficient inventories, tracking of work in progress, etc. To achieve these advantages, however, users or employees must be willing to consistently use the readers. The readers therefore must be easy and convenient to operate.
A variety of scanning systems are known. One particularly advantageous type of reader is an optical scanner which scans a beam of light, such as a laser beam, across the symbols. Laser scanner systems and components of the type exemplified by U.S. Pat. Nos. 4,387,297 and 4,760,248xe2x80x94which are owned by the assignee of the instant invention and are incorporated by reference hereinxe2x80x94have generally been designed to read indicia having parts of different light reflectivity, i.e., bar code symbols, particularly of the Universal Product Code (UPC) type, at a certain working range or reading distance from a hand-held or stationary scanner.
A variety of mirror and motor configurations can be used to move the beam in a desired scanning pattern. For example, U.S. Pat. No. 4,251,798 discloses a rotating polygon having a planar mirror at each side, each mirror tracing a scan line across the symbol. U.S. Pat. Nos. 4,387,297 and 4,409,470 both employ a planar mirror which is repetitively and reciprocally driven in alternate circumferential directions about a drive shaft on which the mirror is mounted. U.S. Pat. No. 4,816,660 discloses a multi-mirror construction composed of a generally concave mirror portion and a generally planar mirror portion. The multi-mirror construction is repetitively reciprocally driven in alternative circumferential directions about a drive shaft on which the multi-mirror construction is mounted. All of the above-mentioned US Patents are incorporated herein by reference.
In electro-optical scanners of the type discussed above, the xe2x80x9cscan enginexe2x80x9d including the laser source, the optics the mirror structure, the drive to oscillate the mirror structure, the photodetector, and the associated signal processing and decoding circuitry all add size and weight to the scanner. In applications involving protracted use, a large heavy hand-held scanner can produce user fatigue. When use of the scanner produces fatigue or is in some other way inconvenient, the user is reluctant to operate the scanner. Any reluctance to consistently use the scanner defeats the data gathering purposes for which such bar code systems are intended. Also, a need exists for compact scanners to fit into small compact devices, such as notebooks.
Thus, an ongoing objective of bar code reader development is to miniaturize the reader as much as possible, and a need still exists to firer reduce the size and weight of the scan engine and to provide a particularly convenient to use scanner. The mass of the moving components should be as low as possible to minimize the power required to produce the scanning movement.
It is also desirable to modularize the scan engine so that a particular module can be used in a variety of different scanners. A need exists, however, to develop a particularly compact, lightweight module which contains all the necessary scanner components.
It is an object of the present invention to reduce the size and weight of components used to produce scanning motion of the light beam, and to collect the reflected light.
A related object is to develop an electro-optical scanning system which is both smaller and lighter in weight.
It is yet a further object to produce a module which may be manufactured conveniently, and at low cost. A related object is to provide a module which may be assembled easily.
According to the present invention there is provided an optical scan module comprising:
(a) a light source for emitting a light beam;
(b) a scanning assembly for receiving said light beam and for generating therefrom a scanning beam directed to an indicia to be read;
(c) a photodetector; and
(d) a one-piece optical element including:
(i) a beam-shaping lens for receiving and shaping said light beam prior to transmission to said scanning assembly; and
(ii) a mirror-defining portion for locating a mirror surface, said mirror surface being arranged to receive reflected light from said indicia and to direct it to said photodetector.
Preferably, the one-piece or integral optical element may be molded from an optically transparent plastics material which is selectively coated to provide the collection mirror reflective surface. The molded member may also define mounting and/or location portions for the light source/laser and/or the photodetector. The photodetector mounting portion may also be coated, preferably with the same material that is used to coat the collection mirror, so as to provide not only optical but also electromagnetic shielding for the photodetector.
The molded member may include downwardly-extending xe2x80x9csnapsxe2x80x9d, allowing the member, along with the mounted laser and photodetector, easily to be secured to an underlying PCB.
Also on the same PCB may be mounted a beam scanning arrangement providing either linear or two-dimensional scanning.
According to the invention there is further provided an optical scan module comprising a mounting base defining a reference plane and having mounted thereon;
a) a light source for emitting a light beam;
b) a scanning assembly for receiving said light beam and for generating therefrom a scanning beam directed to an indicia to be read in which said module is arranged such that the scanning beam defines a scanning plane which is non-orthogonal to the reference plane.
Accordingly the module can be placed on a mother board without the need of spacers to achieve a desired angle.
In another form the invention provides an optical scan module comprising a base defining a reference plane, a beam reflecting element and a beam reflecting element drive, in which the beam reflecting element is mounted relative to the base to be driven to oscillate in a plane angled to a plane orthogonal to the reference plane.
According to the invention there is further provided a small-size optical scan module comprising a substantially rectangular module base and mounted thereon a light source for emitting a light beam, a scanning assembly for receiving said light beam and for generating therefrom a scanning beam directed to an indicia to be read, a detector, and a one piece optical element including a beam shaping lens for receiving and shaping said light beam prior to transmission to said scanning assembly and a mirror defining portion for locating a mirror surface, said mirror surface being arranged to received retro-reflected light and to direct it to said detector.
The invention further provides an optical scan module comprising a light source for emitting a light beam, a first scanning assembly for receiving said light beam and for generating therefrom a scanning beam in a first scanning plane; a second scanning assembly for receiving said scanning beam from said first scanning assembly and for generating a scanning beam also scanning in a second plane non-parallel to the first scanning plane; and a detector for detecting a returning beam in which the light source, the scanning assembly and the detector are provided on a single module base. Accordingly two dimensional scanning is achieved allowing customised scan patterns.
According to the invention there is further provided a scanning element for an optical scanner, the scanning element including a reflector for reflecting a scanning beam and a drive for driving the reflector in a scanning motion in which the reflector is mounted on a torsionally deformable element and is driven in a scanning motion thereon, and in which the torsionally deformable element is elongate, deformable about its elongate axis, and non-planar in cross sectional shape perpendicular to its elongate axis, said cross sectional shape being selected to provide substantially uniform torsional deformation along the elongate axis.
The invention also provides an optical reader comprising a reader housing, and a reading beam generator, a reading beam detector and a reading beam window mounted in the housing, the housing comprising a base, a handle and a head portion, including the reading window, mounted at one end of the handle, the handle being attached at its other end to the base, in which the reader is free-standing on the base. An improved ergonomic including hands-free/free-standing and hand-held use is thus achieved.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. Further features of the invention are set out in the appended independent claims, and further preferred features are set out in the dependent claims.